Method and apparatus for flattening and annealing sheet glass



Dec. 29 1925.

L. R. SCHMERTZ METHOD AND APPARATUS FOR FLATTENING AND ANNEALING SHEET GLASS Filed August 5 1924 5 Sheets-Sheet 1 Dec. 29

L. R. SCHMERTZ METHOD AND APPARATUS FOR FLATTENING AND ANNEALING SHEET GLASS File Aug 5, 1924 '5 Sheets-Sheet 2 $4 @VENT R Dec. 29, 1925.

L. R. SCHMERTZ METHOD AND APPARATUS FOR FLATTENING AND ANNEALING SHEET GLASS 1924 5 Sheets-Sheet 5 Filed August 5,

INVENTOR Patented Dec. 29, 1925.

UNITED STATES LOUIS R. SCHMERTZ, OF JEANNETTE, PENNSYLVANIA, ASSIGNOR TO WINDOW GLASS MACHINE COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF NEW JERSEY.

METHOD AND APPARATUS FOR FLATTENING AND ANNEALING SHEET GLASS.

Application filed August 5, 1924. Serial No. 730,204.

To all whom it may concern Be it known thatI, LOUIS R. SCHMERTZ, a citizen of the United States, residing at Jeannette, county of VVestmoreland, State of Pennsylvania, have invented a new and useful Improvement in Methods and Apparat'us for Flattening and -Ann'ealing Sheet Glass, of which the following is a full, clear, and exact description.

This invention relates to the making of flat sheet glass and is particularly applicable to the flattening oven and connected leer tunnel generally employed in conjunction with the cylinder process of making window glass. In the copending application of Lawrence A. Gessner, SerialNo. 672,530, filed Nov. 3, 1923, there is shown'a leer tunnel wherein compensation is made for the natural shrinkageof the hot gases as they pass from the flattening oven through the leer tunnel. Such an apparatus prevents the ingress of cold air to anysubstantial distance from the delivery end of the leer tunnel and provides a smooth laminar flow of the products of combustion'from the fiattening oven throughthe leer tunnel. The cooling effect is thereby so controlled as to substantially equalize the rate of heat loss from the two faces of the glass sheets and the glass does not become war ed or bowed, but delivered substantially at.

In the copending application of John Hartzell, Serial No. 693,249, filed Feb. 16, 1924, there is shown a form of leer tunnel for. achieving the same result wherein dampers are employed to divert a portion of the heated gases from one of the gaseous streamsto the other, thus ofl-setting the natural tendency of the hotter portionsof the gases to rise to the upper. portions of the leer. Y I have found, however, that when a leer constructed according to either of such 1nventions is used there is a marked tendency toward an increased temperature in thesocalled piling oven. This is probably due to the restriction on the flow of hot gases through the leer tunnel as compared withv leers previously used, so that. the principal outlet for the products ofcombustlon 1s choked oil to a certain extent;

- As a result of this condition the flatteningstonesare increased in temperature and when unflattened glass is placed thereon the stones are a t to burn or mark the lower surfaces 0 the sheets. It will be understood that in aleer of this character the flattening stones are carried on a large wheel so that a stone is first in the flattening oven, where the heat is generally applied and where the operation of flattening is performed, after which the wheel is rotated a sufficient distance to carry the stone with a sheet of flattened glass thereon into a socalled dummy oven of lower temperature, and then through the so-called cooling oven to the piling oven, where the workman lifts the now partially cooled sheet off the stone onto the leer rods. It is necessary to raise the temperature of the glass in the flattenmg oven to above the annealing point of the glass in order to flatten the same and the oven will, of course, be hotter than the glass which it heats, but it is highly desirable to keep the stones relatively cool and supply the requisite heat to the glass from above, since this avoids marking of the glass by the stones, as is well known to those skilled in the flattening art.

Heretofore, this desirable condition of the flattening stones hasbeen easily maintained but, as above stated, the regulation of the flow of gases through the flattening oven in order to prevent warping of the glass during cooling results in an increased temperature on the piling side of the flattening oven, with a consequent loss of opportunity for the stones to cool off .when they are outside the flattening oven proper.

I have found that the burning of the glass may be overcome by. preheating the glass, preferably to very near the annealing temperature. When this is done the glass may be flattened very quickly and the work of the flattener is considerably reduced since the unflattened glass lies down almost immediately and requires only a small 'amount of rubbing. The time required for the actual flattening operation being thus cut down, a material increase in theproduction of the oven may be attained, and with this increased speed I have found that the tendency of the stones to burn the glass is overcome.

The preheating'of the glass cylinders or shawls .is preferably accom lished at a plurality of stations as the un attened glass may be more uniformly heated in this manner and sufiicient time is available to preheat the glass as much as desired even at the highest oven speeds.

In the accompanying drawings illustrating the present preferred embodiment of my invention, p

Figure 1 is a horizontal section taken.on the line II of Figure 2 and showing a ,flattening oven embodying my invention;

Figure 2 is a longitudinal vertical section on the line IIII of Figure 1;

Figure 3 is a view to enlarged scale of ure :1 portion of Figure 1; p

F igure -.t is a vertical section on the line IV-IV of Figure 3;

Figure 5 is a view similar to Figure 4: but showing another posit-ion of the apparatus, and

Figure (3 is a vertical section on the line VIVI of Figure 4.

In the illustrated embodiment of the 1nvention there is shown a flattening oven indicated generally by the reference character 2 and a connected leer tunnel 3. Leer rods 4 are provided for passin glass in sheet form through the. leer an in order to insure the flatness of the product the leer 3 may be provided with a sloping bottom 5, as disclosed and claimed in the above mentioned Gessner application, and also with adjustable dampers 6 as disclosed and claimed in the above mentioned application of'John Hartzell.

The flattening oven is provided with a wheel 7 carrying flattening stones 8 adapted to lie, successively, in. a flattening oven 9, a dummy oven 10, a cooling oven 11 and a piling oven 12 as the wheel 7 is rotated. Heat is supplied in any desired manner, as by burners 13. Heating gases from these burners maintain the flattening oven S) at the desired temperature and then pass under suspended arches 14 which partially separate the flattening oven, the dummy oven, the cooling oven and the piling oven. After passing under these arches a. large portion of the gases travel down the leer tunnel 3 and out the delivery end 15.

As above stated, the provision of the sloping floor 5 and the dampers (3, both of which are exceedingly desirable in the production of unwarped glass, results in a choking off of the flow of gases through the tunnels 15 so that the heating gases must find other outlets. This results in an increased .temperature in the piling oven, cooling oven and the dummy oven, and as a result the stones 8 increase in temperature. lVith an oven operated in this manner burning of the lass is likely to result unless great care is taien.

In accordance with my invention, however, the stick-hole 16 is provided with means for supporting the unflattened glass in' position to be heated by the gases flowing trans from the oven out of the stick-hole. The

, apparatus preferably employed comprises a supports 20 and the lifting frame is moved,

to its upperposition, as illustrated in- Fig- 5. This upward movement is accomplished by a rod 21 and operating levers 22. The levers 22 are connected by downwardly extending rods 23 to cross bars 24, which carry the lifting frame 19. The lower endof the rod 21 is provided with a hook portion 25 adapted to engage notches 26 for holding the lifting frame in raised or lowered position.

\Vith the frame 19 in raised position the traveling frame 17, which is carried by rollers 27, is pulled outwardly by means of a handle 28'until the supports 18 lie adjacent the supports 20. The lifting frame 19 is then lowered, transferring the shawl from the supports 20 to the supports 18. and the traveling frame is shoved inwardly.

At the innermost position of the frame 17 the supports 18 lie adjacent the supports 20 so that the next time the frame 19 is lifted the shawl is transferred from the supports 18 to the supports 20 and when the traveling frame is drawn out and the lifting frame again lowered the shawl is erred to the supports 18. On the next inward movement of the traveling frame 17 there will be two shawls in the stick-hole, occupying the positions shown in Figure 4 and thereafter there will always be two shawls in process of heating. The leading shawl is lifted off the supports 18* by the flattener, who transfers it to the flattening stone in the flattening oven fl. As soon as this shawl has been removed a workman places another shawl ou the support 20 and operates the apparatus as above described to advance the shawl already in the stick-hole from its first position to the position just vacated by the shawl now being flattened, the operation continuing as long as the oven is worked. A vertically adjustable cover 28, provided with a counterweight 29, is provided for the stick-hole.

By reason of the preheating the glass is brought up very close to a suitable flattening temperature before it is placed on the flattening stone, the heating being accomplished in the stick-hole 16. The work of the flattener is thereby materially reduced since the shawl lies down readily and re-.

Ill)

quires only a small amount of rubbing .to

the

increased and because of the increased speed of the wheel the glass is handled without its being burned or marred by the hotter condition of the flattening stone.

1 thus provide for flattening and annealing glass by preheating the unflattened glass to compensate for the increased temperature of the flattening stones induced by the regulation of the gaseous flow from the flattening oven through the .leer. With my invention it is possible to produce flat glass and; at the same time, to materially increase the quality and quantity of the product.

It will be understood that the heat may be supplied at other places than in the particular portion of the apparatus where the flattening operation is carried out, and I use the term flattening oven in its broader sense in the appended claims to signify not only the flattening oven proper, but also the dummy-oven, the cooling oven, and the piling oven.

While I have shown a preferred form of my invention, it will be understood that it is not limited thereto, but may be otherwise embodied within the scope of the following claims.

I claim:

1. In the method of making flat sheet glass, the steps consisting in supplying unflattened glass to a flattening oven, flattening the glass therein, passing it from the oven through a leer to anneal and cool the glass, supplying heating gases to the flattening oven, passing heating gases from the flattening oven through the leer in streams above and below the glass, so regulating the relative rate of flow of gases above and below the glass as to equalize the rate of cooling from the two faces of the glass therein, and preheating the. unflattened glass supplied to the flattening oven to compensate for the increased temperature of the surfaces conlat-ting with the glass in the flattening oven induced by the; regulation of the gaseous flow from the flattening oven through the, leer.

2. In the method of making flat sheet glass, the steps consisting in supplying unflattened glassto a flattening oven, flattening the glass therein, passing it from the oven through a. leer to anneal and cool the fluid from the flattenin glass, supplying heating gases to the flattening oven, passing heating gases from the flattening oven through the leer in streams above and below the glass, so regulating the relative rate of flow of the gases above and below the glass as to equalize the rate of cooling from the two faces of the glass therein, and preheating in a plurality of stages the unflattened glass supplied to the flattening oven to compensate for the increased temperature of the surfaces contacting with the glass in the flattening oven induced by the regulation of the gaseous flow from the flattening oven to the leer.

3. In the method of making flat sheet glass, the steps consisting in supplying unflattened glass to a flattening oven. flattening the glass therein, passing it from the oven through a leer to anneal and cool the glass, supplying heating gases to the flattening oven, passing heating gases from the flattening oven through the leer in streams above and below the glass, so regulating the relative rate of flow of the gases above and below the glass as to equalize the rate of cooling from the two faces of the glass therein, and preheating to near flattening temperature the unflattened glass supplied to the flattening oven to reduce the time of contact of the glass with the surfaces contacting therewith in the flattening oven and thus compensate for the increased temperature of such surfaces induced by the regulation of the gaseous flow from the flattening oven to the leer.

4. Apparatus for making flat sheet glass, including a flattening oven and connected leer tunnel, the tunnel being of restricted area and adapted for the passage of gaseous oven through the leer, and means for pre eating the unflattened glass supplied to the flattening oven.

5. Apparatus for making flat sheet glass including a flattening oven and connected leer tunnel, the tunnel being of restricted area and adapted for the passage of gaseous fluid from the flattening oven through the leer, and means for preheating in a plurality of stages the unflattened glass supplied to the flattening oven.

In testimony whereof I have hereunto set my hand.

LOUIS R. SCHMERTZ. 

